1. Field of the Invention
The present invention relates generally to adjustment devices for fluid control apparatus, and more particularly to a means for permitting the adjustment of a vacuum modulator spring load control shaft or screw by means other than an external tool such as a screwdriver or wrench, and without removing the continuous fluid or vacuum line to make the adjustment.
The invention has particular application to an automobile transmission vacuum modulator to make adjustments easier and more accurate.
This application is a continuation-in-part of my co-pending application entitled "Modulator Adjustment Device", Ser. No. 07/335,714, filed Apr. 10, 1989, and is related to my co-pending application entitled "Apparatus for Remotely Adjusting Transmission Vacuum Modulators", Ser. No. 498,719, filed Mar. 26, 1990, both of which are incorporated herein by reference.
2. Description of the Prior Art
The original vacuum modulator on automobile transmissions were not adjustable and merely included a vacuum line connected to a tube fitting on the transmission's vacuum modulator. As the engine speeded up and engine manifold vacuum increased with the engine's acceleration, the vacuum pulled on the diaphragm inside the modulator, and the diaphragm moved proportionately. The diaphragm was used to move a rod in and out of the transmission causing gear shifting to take place. The tension on the diaphragm and thus the amount of vacuum required to move the diaphragm enough to cause shifting could not be adjusted.
The more recent generation of vacuum modulators have a screw in the tube fitting and include some type of airway to allow air to flow through a passageway extending along the length of the screw. The purpose of the screw is to adjust the tension of a spring biased against the diaphragm in the modulator. When the screw is turned to increase the pressure of the spring against the diaphragm, a higher vacuum is required to cause shifting, and thus the transmission will be shifted at a higher speed.
The adjustment of the screw is achieved by removing the vacuum line, inserting a tool into the tube fitting to turn the screw, and then reconnecting the vacuum line. This is a difficult and time-consuming "cut and try" process, since the screw cannot be seen inside the tube fitting, thus accurate adjustments cannot be easily made. Any service technician would prefer to have a device in the line to the modulator to adjust the screw, rather than using a tool to make the adjustments.